Final answer:
Sancho lacks support from friends brave enough to join a fight, leaving him unable to assist Don Quijote in a battle.
Step-by-step explanation:
Sancho cannot help Don Quijote if he gets into another fight because he lacks the support of friends who are brave enough to stand by him in violent confrontations. From the given statement, "Fight! How? Even if I would, I haven't a friend except that boy who doesn't dare stay in the village." it is evident that Sancho feels isolated and recognizes that the only person who might be a potential ally is a boy who is too afraid to remain in the village, let alone assist in a fight. This isolation and absence of courageous companions leaves Sancho unable to provide assistance in combative situations.